GCN Circular 29559

M. H. Siegel (PSU) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210222B
101 s after the BAT trigger (Gropp et al., GCN Circ. 29545
Not found
 
 
).
A source consistent with the XRT position (Gropp et al. GCN Circ. 29545
Not found
 
 
)
is detected in the initial UVOT exposures. This source is also consistent
with previously reported optical detections (Hu et al., GCN Circ. 29546
Not found
 
 
; 
Strausbaugh, GCN Circ. 29547
Not found
 
 
; Mong et al., GCN Circ. 29548
Not found
 
 
; Parley, GCN Circ.
29549
Not found
 
 
; Zhu et al., GCN Circ. 29551
Not found
 
 
, Lipunov et al., GCN Circ. 29554
Not found
 
 
). We note
that the lack of detection in the NUV passbands would be consistent with the
redshift of 2.198 reported by Agui Fernandez et al. (GCN Circ. 29552
Not found
 
 
).

The preliminary UVOT position is:
   RA  (J2000) =  10:18:25.43 = 154.60595 (deg.)
   Dec (J2000) = -14:55:55.1  = -14.93198 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              101          250          147         16.89 +/- 0.03
v                  588          608           19         16.80 +/- 0.17
b                  515          534           20         17.24 +/- 0.12
u                  259          508          246         16.82 +/- 0.04
w1                 639         1793          124        >18.8
m2                 614         1606           78        >20.1
w2                 564         1732          136        >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.102 in the direction of the burst
(Schlegel et al. 1998).